The present invention relates to a method and system for assisting in the spotting of a movable mold core. The present invention includes the use of a movable core spotting apparatus that allows the necessary spotting to take place in a more efficient manner than is currently possible.
An increasing number of products are being produced today via some type of molding process. A multitude of products, once manufactured from metallic compounds, for example, are now produced from lighter and less expensive materials, such as, for example, plastics. The use of such materials and manufacturing techniques often allows for a product of fewer components and of lighter weight, but one that also retains sufficient strength.
Not only has the number of products produced via molding techniques increased, but so has the complexity of the products. Whether produced by injection, compression or other molding methods, molded products now often have complex geometries. Such geometries require generally more complicated molds and manufacturing methods. For example, modem plastic molds are often equipped with one or more slidable, or similarly movable cores, to form features such as undercuts not otherwise producible.
A typical mold, such as an injection mold, is generally comprised of two mold halvesxe2x80x94one half containing a main cavity, and the other half having a main core. During mold development, a process generally referred to as spotting is used to ensure that clearances and areas of designed contact (shutoff) between mold halves are satisfactory. Spotting compound or another suitable marking product is generally applied to these areas of concern, and the mold is placed into a spotting press, which allows the mold halves to be repeatedly separated and reacquainted. In this manner, areas of the mold that should show contact, and do not, may be built up; while areas that should not show contact, and do, may be ground down. The spotting process may be repeated until the proper relationship between mold areas is achieved.
Just as is done with respect to the main mold halves, spotting is also used to ensure that the fit between the movable core, or cores, and the portion of the mold that receives each movable core is proper. With respect to a movable core, however, the spotting technique described above is generally not practicable. Because movable cores often move transversely, or otherwise at an angle to the general direction of movement of the main mold halves, a spotting press is generally not capable of imparting the proper plane of motion to a typical movable core. To accomplish spotting of a movable core, the mold half that communicates therewith is usually set on a work table or similar apparatus, and in a position that will allow the mating portion of the mold to best receive the movable core while still permitting access thereto for making adjustments. The movable core is then typically placed, by hand, into proper relation with the mold half, and checked for fit by placing spotting compound on areas of concern and manually causing the movable core to be set to, and retracted from the mold. Adjusting the fit of the movable core to the mold typically requires numerous repetitions of setting and retracting the movable core, and welding and/or grinding on one, or both, of the movable core and the mating portion of the mold.
While manual manipulation of movable cores may be acceptable for smaller molds, on molds of relatively large size the movable cores may themselves exhibit substantial dimensions. Large movable cores are generally designed to be moved by a mating mold component or by hydraulic power derived from a molding press during the molding cyclexe2x80x94not by hand. Thus, with the intended method of movable core actuation generally not available for use during the spotting process, fitting a large movable core to a mold for spotting may require the use of, for example, a crane, pry bars, hammers and various other tools to lift the movable core into position and simulate its motion. For example, a crane may be required to lift the movable core to the mold, pry bars may be used to place the movable core into contact with the mating portion of the mold, and a slide hammer or similar device may be used to retract the movable core therefromxe2x80x94after which the crane may again be required to remove the movable core to another location where operations such as grinding or welding may be performed thereon.
As the number of adjustments required to place the movable core and mating mold portion into proper relation may be considerable, a substantial expenditure of time by the person or persons performing the spotting operation is often required. In addition, the frequent handling of large movable cores by this technique also presents an increased possibility of damage to the main mold portion and movable mold cores. Therefore, it would be advantageous during the mold development process if it were possible to spot a movable core without having to repeatedly remove the movable core from the mold.
The present invention satisfies this need. The present invention discloses a movable mold core spotting method and apparatus that enables a mold, or a portion thereof, to be placed on a support structure or similar device designed to receive the mold and ensure its position. Each movable core requiring spotting is placed and aligned with the portion of the mold to which the movable core mates. A coupling means is provided for connection to each of the movable cores needing spotting. Each coupling means is further connectable to a force exerting device, such as, for example, a hydraulic cylinder, that may be activated to cause movement of the movable core or cores to which it is attached. Preferably, the force exerting device, or devices, are located substantially beneath the support structure, but alternatively, may be located outboard of each movable core. The location of each hydraulic cylinder or other force exerting device is preferably adjustable in three dimensions to provide for differences in location, center of mass, stroke length and other characteristics of the different movable cores to which the hydraulic cylinders will be attached. Other force exerting devices may also be employed depending upon the size of the movable cores involved, including, for example, pneumatic cylinders, and electric motors and gear assemblies.
When a hydraulic cylinder is provided to move a movable core, a hydraulic pump and reservoir is also provided to supply pressurized hydraulic fluid to the cylinder. Upon actuation of the hydraulic cylinder, the movable core may be set to, or retracted from, the mating portion of the mold without physical exertion by the worker involved. A flow control or similar device is preferably provided to afford control over the speed of movement of the movable core. The apparatus of the present invention is also preferably capable of retracting the movable core to a position which allows for ample accessibility to both the movable core and the section of the mold with which the movable core communicates.
Thus, the method and system of the present invention allows for the effective and efficient spotting of one or more movable mold cores, wherein the installation and removal of the movable core to the mold is minimized, and required movement of the movable core is accomplished by a force exerting device. The present invention minimizes damage to mold components, while also reducing the time necessary to successfully perform the core spotting operation.